JP2018019494A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle motor capable of achieving high airtightness of a penetration hole formed in a base plate and which has high workability.SOLUTION: A spindle motor comprises: a base plate which held a stator core in which a coil is wound and an axial body on a first surface side, holds a wiring substrate on a second surface side opposite to the first surface, and in which a penetration hole is formed from the first surface to the second surface; a rotter assembly capable of being rotated about the axial body as a center; a conducting wire that is led from the coil and is connected to the wiring substrate through the penetration hole; and a sealing agent that separates an inner peripheral surface of the penetration hole and the conducting wire and seals the penetration hole. The inner peripheral surface of the penetration hole is formed so that a diameter becomes small from the first surface to the second surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a spindle motor.

  Conventionally, spindle motors used for hard disk drives are known. In a hard disk drive, the entire hard disk drive including the spindle motor is required to be hermetically sealed in order to prevent contaminants such as dust from adhering to the hard disk. Furthermore, in a hard disk drive filled with a gas other than air, such as helium, higher gas tightness is required because the filled gas is not leaked to the outside.

  By the way, the spindle motor includes a stator fixed to the base plate and a rotor that rotates around the stator. The stator includes a stator core and a coil wound around the stator core. In a spindle motor, generally, FPC (Flexible Printed Circuits) is arranged on the back surface opposite to the coil via a base plate. For this reason, the base plate is formed with a through hole through which a lead wire from the coil is inserted. The lead wire from the coil is drawn to the back surface side of the base plate through the through hole, and is electrically connected to the FPC by soldering or the like.

  Here, the through hole needs to be securely sealed in order to ensure airtightness. For example, Patent Document 1 discloses a configuration in which a through hole is sealed with a sealing resin.

JP-A-8-275433

  However, in the configuration of Patent Document 1, since the sealing resin only covers one side of the through hole, the airtightness is not high. In this configuration, it is conceivable to cover both sides of the through-hole with a sealing resin, but workability is deteriorated because the number of processes increases.

  The present invention has been made in view of the above, and an object of the present invention is to provide a spindle motor that achieves high airtightness of a through hole formed in a base plate and has good workability.

  In order to solve the above-described problems and achieve the object, a spindle motor according to an aspect of the present invention holds a stator core around which a coil is wound and a shaft body on a first surface side, and a wiring board is mounted on the first surface. A base plate that is held on the second surface side opposite to the first surface and has a through hole formed from the first surface to the second surface; a rotor assembly that can rotate about the shaft; and the coil A conductive wire that is drawn from the through-hole and connected to the wiring board through the through-hole, and a sealing agent that isolates the inner peripheral surface of the through-hole and the conductive wire and seals the through-hole. And the inner peripheral surface of the through hole is formed such that the diameter decreases from the first surface toward the second surface.

  In the spindle motor according to one aspect of the present invention, an insulating film is disposed between the coil and the first surface, and a notch is formed on an outer periphery of the insulating film, At least a part of the cutout part is overlapped with at least a part of the opening in the second surface of the through hole in a plan view.

  In the spindle motor according to one aspect of the present invention, at least the end of the through hole on the second surface side has a diameter that increases toward the boundary between the inner peripheral surface of the through hole and the second surface. A chamfered portion is formed.

  Further, in the spindle motor according to one aspect of the present invention, the wiring board is formed with a lead-out hole for drawing out the lead that has passed through the through-hole, and the lead-out hole is sealed with solder. It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, while realizing the high airtightness of the through-hole formed in the baseplate, it is possible to realize a spindle motor with good workability.

It is a longitudinal cross-sectional view of the spindle motor which concerns on embodiment of this invention. It is the elements on larger scale of the spindle motor shown in FIG. It is explanatory drawing which expands and shows a through-hole and an insulating film from the 1st surface side. It is explanatory drawing which expands and shows a through-hole and an insulating film from the 1st surface side.

  Embodiments of a spindle motor according to the present invention will be described below with reference to the drawings. In the drawings illustrated below, the same or corresponding elements are denoted by the same reference numerals as appropriate. It should be noted that the drawings are schematic, and the relationship between the dimensions of each element, the ratio of each element, and the like may differ from the actual situation. Even between the drawings, there are cases in which portions having different dimensional relationships and ratios are included.

(Embodiment)
FIG. 1 is a longitudinal sectional view of a spindle motor according to an embodiment of the present invention. As shown in FIG. 1, the spindle motor 100 includes a base plate 1 serving as a base, a shaft 2 (shaft body) and a stator core 3 fixed to the base plate 1, and a rotor assembly that can rotate around the shaft 2. It has. The spindle motor 100 is a spindle motor used for a hard disk drive filled with helium.

  The base plate 1 is made of, for example, an aluminum alloy, and includes a first surface P1 positioned on a side (upper side in FIG. 1) to which the stator core 3 is fixed, and a second surface P2 opposite to the first surface P1 in the axial direction. Have.

  A first conical bearing member 21 having a conical outer surface and a second conical bearing member 22 are fixed to the shaft 2 so as to be spaced apart from each other in the axial direction. The rotor assembly includes a sleeve 23 having a shaft insertion hole through which the shaft 2 is inserted, a rotor hub 24 fixed to the outer periphery of the sleeve 23, a back yoke 6 and a ring magnet 5 fixed to the rotor hub 24. The shaft insertion hole of the sleeve 23 has a first conical inner surface 25 and a second conical inner surface 26 at each end. The first conical inner surface 25 and the second conical inner surface 26 are opposed to the first conical bearing member 21 and the second conical bearing member 22 through a minute gap, respectively. Lubricating oil is filled in the minute gaps between the first conical bearing member 21 and the first conical inner surface 25 and between the second conical bearing member 22 and the second conical inner surface 26. Further, at least one of the first conical inner surface 25 and the second conical inner surface 26 or the conical outer surfaces of the first conical bearing member 21 and the second conical bearing member 22 is formed with a dynamic pressure generating groove, and the fluid dynamic pressure bearing. The bearing part by is formed. With the above configuration, the rotor assembly is supported on the first surface P1 side of the base plate 1 via the bearing portion of the fluid dynamic pressure bearing during rotation. A stator core 3 around which the coil 4 is wound is fixed on the first surface P1 side of the base plate 1 so as to face the ring magnet 5. The ring magnet 5 is a permanent magnet that is magnetized with its polarity reversed in the circumferential direction, and the back yoke 6 suppresses leakage of magnetic flux from the ring magnet 5. The stator core 3 has a structure in which magnetic steel sheets processed into an annular shape are stacked. The stator core 3 extends radially outward from the outer periphery of the bearing portion, and a plurality of pole teeth are provided apart from each other in the circumferential direction of the stator core 3. A coil 4 is wound around each pole tooth. A wire (conductive wire) 4 a is drawn from the coil 4. By passing an electric current through the coil 4 and switching its polarity, the magnetic attraction force and the magnetic repulsion force generated between the ring magnet 5 and the pole teeth of the stator core 3 are switched, and the shaft 2 in which the rotor assembly is fixed to the base plate 1. Around the base plate 1. When the rotor assembly rotates at high speed, dynamic pressure is generated in the bearing portion, and the rotor assembly rotates while being supported in a non-contact state with respect to the shaft 2, the first conical bearing member 21, and the second conical bearing member 22. .

  Next, connection of the wire (conductive wire) 4a drawn from the coil 4 will be described. FIG. 2 is a partially enlarged view of the spindle motor shown in FIG. In the base plate 1, a through hole 1a for drawing out a wire (conductive wire) 4a is formed from the first surface P1 to the second surface P2. The wire 4a is inserted from the first surface P1 side, passes through the through hole 1a, and is drawn out to the second surface P2 side. A wiring substrate 9 is provided on the second surface P <b> 2 of the base plate 1. The wiring board 9 is, for example, a flexible printed circuit board (FPC: Flexible Printed Circuits) in which a wiring pattern is formed on a resin film, and is bonded to the second surface P2 of the base plate 1 with an adhesive or the like. . The wiring board 9 is formed with a lead-out hole 9a for drawing out the wire 4a. As shown in FIG. 2, the end portion of the wire 4 a that has been drawn from the second surface P <b> 2 side and passed through the lead wire drawing hole 9 a is electrically connected to the wiring on the wiring board 9 by the solder 10.

  The through hole 1a is formed in a tapered shape whose diameter decreases from the first surface P1 side toward the second surface P2 side. In the following description, the inner peripheral surface of the tapered through hole 1a is referred to as “tapered portion 1aa”. The diameter of the tapered portion 1aa is maximized at the end portion on the first surface P1 side and is minimized at the end portion on the second surface P2 side. Here, the minimum diameter of the tapered portion 1aa (for example, the diameter of the end portion on the second surface P2 side) is preferably about twice the thickness of the wire 4a from the viewpoint of improving workability. On the other hand, the maximum diameter of the taper portion 1aa (for example, the diameter of the end portion on the first surface P1 side) is about 7 times the thickness of the wire 4a from the viewpoint of sealing the through hole 1a with the sealant 8 described later. It is preferable that it is below a grade.

  A chamfered portion 1ab whose diameter increases toward the boundary between the inner peripheral surface of the through hole 1a and the first surface P1 is formed at the end of the tapered portion 1aa on the first surface P1 side. On the other hand, a chamfered portion 1ac whose diameter increases toward the boundary between the inner peripheral surface of the through hole 1a and the second surface P2 is formed at the end of the tapered portion 1aa on the second surface P2 side.

  Here, in the state where the wire 4a is drawn out from the lead wire drawing hole 9a, helium filled in the hard disk drive leaks to the outside from a slight gap between the inner peripheral surface of the lead wire drawing hole 9a and the wire 4a. There is a fear. Therefore, in the present embodiment, the diameter of the conductor drawing hole 9a is set to be smaller than the diameter of the through hole 1a of the base plate 1 in the second surface P2, and the conductor drawing hole 9a overlaps the through hole 1a in plan view. The gap between the wire 4a and the inner peripheral surface of the lead wire drawing hole 9a and the wire 4a is completely sealed with the solder 10 in a state where the wire 4a passes through the lead wire drawing hole 9a.

  The spindle motor 100 according to the present embodiment includes an insulating film 7, a sealant 8, and a wiring substrate 9 in addition to the above configuration. The insulating film 7 is formed of an insulating material such as plastic, is disposed between the coil 4 and the first surface P1 of the base plate 1, and is adhered to the first surface P1 of the base plate 1 with an adhesive or the like. .

  The sealing agent 8 is injected into the through hole 1a, isolates the inner peripheral surface of the through hole 1a from the wire 4a, and seals the through hole 1a. The sealant 8 is an adhesive made of resin, for example.

  Next, the arrangement | positioning aspect of the through-hole 1a and the insulating film 7 is demonstrated. 3 and 4 are explanatory views showing the through hole 1a and the insulating film 7 in an enlarged manner from the first surface P1 side. In FIG. 3, the coil 4, the stator core 3, and the sealant 8 are omitted from the viewpoint of facilitating understanding of the description. As illustrated in FIGS. 3 and 4, a cutout portion 7 a having a predetermined diameter is formed on the outer periphery of the insulating film 7. In the present embodiment, a cutout portion 7a formed in a semicircular shape is illustrated. The diameter of the cutout portion 7a is smaller than the diameter of the end portion on the second surface P2 side of the tapered portion 1aa. As will be understood from the above description, at least a part of the notch portion 7a is disposed so as to overlap with the opening of the end portion on the second surface P2 side of the tapered portion 1aa in plan view (FIGS. 3 and 4). .

  As described above, according to the present embodiment, the through hole 1a is formed so that the diameter decreases (for example, in a tapered shape) from the first surface P1 toward the second surface P2. In this configuration, when the sealing agent 8 is injected into the through-hole 1a, the workability can be improved by injecting the sealing agent 8 from the first surface P1 side having a large diameter. Further, since the sealing agent 8 injected from the first surface P1 side of the tapered portion 1aa flows into the second surface P2 side having a small diameter due to capillary action, the entire tapered portion 1aa of the through hole 1a is sealed with the sealing agent 8. Is surely sealed. As a result, it is possible to achieve high airtightness of the through hole 1a as compared with the configuration in which only the first surface P1 side or the second surface P2 side of the through hole 1a having a constant diameter is sealed with a sealant. It is. As understood from the above description, according to the configuration of the present embodiment, it is possible to realize both high airtightness of the through hole 1a formed in the base plate 1 and improvement of workability. .

  Further, according to the present embodiment, since the through hole 1a has the chamfered portion 1ab and the chamfered portion 1ac, the sealing agent 8 injected into the tapered portion 1aa protrudes outside the first surface P1 or the second surface P2. Is prevented. That is, the end of the through hole 1a on the first surface P1 side is formed so that its diameter increases toward the boundary between the inner peripheral surface of the through hole 1a and the first surface P1, and the second surface of the through hole 1a. The end portion on the P2 side is formed so that the diameter becomes larger toward the boundary between the inner peripheral surface of the through hole 1a and the second surface P2. Specifically, as illustrated in FIG. 2, a chamfered portion 1ab is formed on the first surface P1 side of the tapered portion 1aa, and a chamfered portion 1ac is formed on the second surface P2 side. According to the above configuration, since the sealing agent 8 injected into the tapered portion 1aa is held by the chamfered portion 1ab and the chamfered portion 1ac, the sealing agent 8 injected into the tapered portion 1aa becomes the first surface P1. Or the situation which protrudes outside the 2nd surface P2 is prevented. In particular, when the sealing agent 8 is injected from the first surface P1 side, there is a possibility that the sealant 8 may protrude outside the second surface P2 on the opposite side. Since the sealing agent 8 flowing into the second surface P2 side is held by the chamfered portion 1ac by the capillary phenomenon based on the same principle, it is prevented from protruding outside the second surface P2, and the injection operation of the sealing agent 8 is easy. become.

  Moreover, in this Embodiment, the semicircle-shaped notch part 7a which has a predetermined | prescribed diameter is formed on the outer periphery of the insulating film 7, and the diameter of the notch part 7a is the edge part in the 2nd surface P2 side of the through-hole 1a. When the wire 4a is inserted into the through hole 1a from the first surface P1 side, the wire 4a contacts only the notch 7a of the insulating film 7 and does not contact the inner peripheral surface of the through hole 1a. Further, since at least a part of the notch portion 7a is arranged so as to overlap with the diameter of the end portion on the second surface P2 side of the inner peripheral surface of the base plate 1 in which the through hole 1a is formed, the wire 4a is Even when it is pulled out from the second surface P2, it does not contact the inner peripheral surface of the base plate 1. According to the above configuration, contact between the wire 4a and the inner peripheral surface of the through hole 1a is prevented, and therefore no gap is generated due to contact between the wire 4a and the inner peripheral surface of the through hole 1a. Therefore, it is possible to reliably prevent the helium filled in the hard disk drive from leaking to the outside and realize high airtightness.

  In the embodiment, the shaft fixing type spindle motor 100 in which the rotor assembly rotates around the shaft 2 fixed to the base plate 1 is exemplified. However, the rotor assembly is also suitably used for the shaft rotating type spindle motor in which the shaft rotates together with the rotor assembly. Can be done.

  In the embodiment, the configuration in which the chamfered portions are formed on both the end portion on the first surface P1 side and the end portion on the second surface P2 side of the tapered portion 1aa is illustrated. It is good also as a structure where a chamfering part is formed only in the edge part by the side of the 2nd surface P2 of the internal peripheral surface of the hole 1a. Also with this configuration, the sealing agent 8 injected into the tapered portion 1aa from the first surface P1 side is held by the chamfered portion 1ac, so that the sealing agent 8 injected into the tapered portion 1aa is attached to the inner wall of the base plate 1. The effect that the situation which protrudes from the outside is prevented is realized.

  In the embodiment, the configuration in which the semicircular cutout portion 7a having a predetermined diameter is formed on the outer periphery of the insulating film 7 is illustrated, but the cutout portion 7a may have any other shape (for example, a semi-cutout portion 7a). A circular shape other than a circle, a substantially circular shape such as an ellipse, a substantially semicircular shape including a semi-elliptical shape, a concave shape, a V shape, a polygonal shape, etc.) may be employed. Even with the configuration exemplified above, it is possible to prevent the occurrence of a gap due to the contact between the wire 4a and the inner peripheral surface of the through hole 1a, so that the air tightness of the through hole 1a is realized and the hard disk drive is filled. It is possible to reliably prevent the leaked helium from leaking outside.

  In the embodiment, the spindle motor used for the hard disk drive filled with helium has been described as an example. However, the present invention can also be applied to a spindle motor used for a hard disk drive not filled with helium.

DESCRIPTION OF SYMBOLS 1 Base plate 1a Through-hole 1aa Tapered part 1ab, 1ac Chamfering part 2 Shaft 3 Stator core 4 Coil 4a Wire 5 Ring magnet 6 Back yoke 7 Insulating film 7a Notch part 8 Sealant 9 Wiring board 9a Conductor extraction hole 10 Solder 21 1st cone Bearing member 22 Second conical bearing member 23 Sleeve 24 Rotor hub 25 First conical inner surface 26 Second conical inner surface 100 Spindle motor P1 First surface P2 Second surface

Claims (4)

The stator core around which the coil is wound and the shaft body are held on the first surface side, the wiring board is held on the second surface side opposite to the first surface, and extends from the first surface to the second surface. A base plate in which a through hole is formed;
A rotor assembly rotatable about the shaft body;
A conductive wire drawn from the coil and passing through the through hole and connected to the wiring board;
A sealant that isolates the inner peripheral surface of the through hole and the conductive wire and seals the through hole;
The spindle motor, wherein an inner peripheral surface of the through hole is formed to have a diameter that decreases from the first surface toward the second surface. An insulating film is disposed between the coil and the first surface,
A cutout is formed on the outer periphery of the insulating film,
2. The spindle motor according to claim 1, wherein at least a part of the notch overlaps at least a part of an opening in the second surface of the through hole in plan view. A chamfered portion whose diameter increases toward the boundary between the inner peripheral surface of the through hole and the second surface is formed at least at the end of the through hole on the second surface side. The spindle motor according to claim 1 or 2. In the wiring board, a lead wire lead-out hole for drawing out the lead wire that has passed through the through hole is formed,
The spindle motor according to any one of claims 1 to 3, wherein the lead wire drawing hole is sealed with solder.